Question

a) An ambident nucleophile is ………

i) Ammonia

ii) Ammonium ion

iii) Chloride ion

iv) Nitrite ion

b) Haloalkanes and Haloarenes are organohalogen compounds.

i) Suggest a method for the preparation of alkyl chloride.

Answer 1

a) iv) Nitrite ion

b) i) Alkyl chlorides can be prepared by passing dry hydrogen chloride gas through a solution of alcohol or by heating a solution of alcohol in concentrated aqueous HCI in presence of anhydrous zinc chloride as a catalyst.

Or, by the action of alcohols with PCl₃, PCI₅ or SOCI₂.

3R-OH + PCl₃ → 3R-CI + H₃PO₃

R-OH + PCl₅ → R-CI + POCl₃ + HCl

R-OH + SOCl₂ → R-CI + SO₂ + HCl

Or, chlorination of hydrocarbons in presence of light or heat.

 eg. CH₃CH₂CH₂CH₃Cl₂ \(\underset{or heat}{\stackrel{Cl_2 NV light}{\longrightarrow}}\) CH₃CH₂CH₂CH₂Cl+CH₃CH₂CH(Cl)CH₃

Or, by the addition of hydrogen chloride to alkenes.

eg. CH₂=CH₂+HCl→CH₃−CH₃